[keycloak-user] Automatic Client registration: Assign roles to service account

Hello, We are currently trying to use client registration policy, so our services can register themselves in Keycloak. The registration itself works perfectly, but we have one (big) issue: we do not know, how to assign roles to the associated service account in the ClientRepresentation (as without roles for the client, the registration is a bit useless for us). Is there any way, how to assign roles (client roles of other services in our case) to service account during automatic registration? Or do we need an admin account to do that. Thanks, Pavel